Phonographic recording



Dec. 2, 1930. H. s. WORRELL I 1,783,761

PHONOGRAPHIC RECORDING Original Filed Dec. 3, 1925 INVENTOR. Y f/awarz/S Worl'ell,

Patented Dec. 2, 1930 UNITED STATES PATENT OFFICE" HOWARD SELLERS WOF'BELL, OF ARDMORE, PENNSYLVANIA, ASSIGNOR TO DICTA PHONE CORPORATION, OF BRIDGEPORT, CONNECTICUT, A CORPORATION OF NEW roan rnolvoeaarmc miconnme Application filed December a, 1925, seriai'no. 72,904. Renewed April 17, 1929.

been proposed to discard the diaphragm and provide the recording stylus with means.

whereby it is directly operated by an electromagnet.

Both theseproposals are predicated upon the use of an electromagnet with an armature and in: such devices, difiiculty is usually experienced in adjusting the armature properly to operate. For, as is well known, the pull of an electromagnet upon its armature varies with distance between the armature and the core of the electromagnet. Consequently, a slight variation in this distance might render the device practically inoper-- the armature with respect to the electromagnet core;

An object of this invention is to avoid these-difliculties and this is accomplished by utilizing a solenoid and core instead of an electromagnet and armature for the actuation of the stylus. The use of a solenoid is advantageous since the air gap or space between the actuating coil and the core may be made substantially invariable.

Another difliculty heretofore experienced with electrical recording has been in the accommodation of the recording stylus to records of different thicknesses, it having been found necessary'to move the electromagnet toward and from the record bodily to accommoda'te for the differences in diameters of the records between a new record and one' made for a small, yet important, rise and fall of the recording stylus during the rotation of the record.

To permit these two results to be obtained, a certain amount of weight was believed to be necessary and was employed to hold the stylus in proper operating position. Yet it was found that when the weight was made sufiiciently heavy to do this, the parts had so much inertia as to prevent them from func tioning prolperly.

' These di culties have'been overcome .by the present invention by employing electrical means for maintaining the stylus in proper recording position at the proper time.

Accordingly, the preferred embodiment of this invention may comprise a solenoid which itself operates to produce the recording movements'of the stylus, and which, actuated by the carrier current used in the electrical transmission ,of sound to be recorded, moves the recording stylus into recording contact during the recording operation.

This feature also avoids another difliculty heretofore experienced in recording sound by either electrical .or mechanical means, and that is the necessity ofproviding special mechanism for raising the stylus from the record surface when it is not desired to record, or when it is desired to do something else, for instance, when reproducing or when removing the record from the machine. This difliculty is obviated by the present invention because biasing means may be provided for contact with the record and maintains such returning the stylus to inoperative position out of engagement with the record so soon as the carrier current for the electrically transmitted sound ceases.

' Another important feature of the present invention is the provision of improved means for mounting the stylus and its actuating parts, for, accordingto the present invention, the stylus is mounted on knife edges and the actuating link is also mounted on knife edges so asto reduce to a minimum the friction between these relatively m'ovin parts and stationary parts which support t em.

' Other improvements and advantages will hereinafter appear.

a Fig. 4 is a diagrammatic view, showing improved means for operat1ng electric record ing devices.

As shown in the accompanying drawing, the phonograph comprises a base 10"having an upright 11 which supports a mandrel 12 for a record .13. Mounted on the base 10 are transverse uide rods 14 which support a carriage 15 or movement across the machine. The carriage 15 may be provided with the usual or conventional sound-box. 16 having a reproducing stylus 17 for reproducing sounds recorded on the record 13. This reproducing stylus 17 is mounted on a holder 18 pivotally mounted on a weighted lever ,19, and the stylus holder 18 is connected by a wire or link 20 to .a diaphragm 21.. Preferably, t is? sound-box 16 fits an opening 22 provided in the carriage adapted to receive 16.

According to the present invention, the

recording mechanism preferably comprises.

a coil 23 mounted on a base 24 removably fitting an opening 25 provided in the carriage 15. The coil 23 is not provided with a magnetic core, but, of course, may be wound upon a fibrous core onother non-magnetic core, or it may be wound on a core which is later removed from the coil, whereupon the wires of the coil may beheld together by a sizing material if desired.

The recording stylus 26, according to the present invention, is mounted on a stylus holder 27 whose forward end is forked (see Fig. 2) to provide a pair'of arms 28 in which there is inserted" a transversely disposed knife-edge bar 29. This .knife-edgebar 29 engages a depending lug 30 which is proed at its lower end with a. knife-edge receiving portion, as shown.

To actuate the stylus26 and its holder 27 to record sound vibrations and to move the stylus 26 into record engaging or recording positions on records of di rent thicknesses,

the stylus holder 27 is connected to a rod or.

core 31 which passes through the hollow center of the coil 23. This rod 31 ispreferably made of iron so as to be acted upon magnetically by the magnetic field produced by the coil 23. The connections between the rod 31 and the stylus holder 27 preferably comprise a transverse knife-edge bar 32 set in forked arms v33 of the rearward end of the stylus holder 27 and a knife-edge receivingnotch 34 provided on the rod 31, preferably near its end.

The stylus holder 27. is held in engagement with its supporting lug 30 and in engagement with the rod 31 by a spring 35 which exerts pressure rearwardly on the rod 31 and tends to draw the stylus holder 27 rearwardly through the engagement of the knife-edge receivlng notch 34: with the knife-edge bar '32, and hence, draws the knife-edge bar 29 firmly against the lug 30 which acts as a fulcrum for the stylus holder.

' At is upper end, the rod 31 may be guided by any suitable means which will tend to cause the rod to have a movement within the coil 23 as nearparallel to the axis of the coil as practicable, and yet which will not increase or add appreciably to the friction of the moving parts of the device.

This means, according to the present invention, preferably comprises a knife-edge bar 36 having a knife-edge in engagement with a notch 37 in the rod 31 and a knife-edge in engagement with a notch 38 in a part connected to the head 24 in some suitable way. The upper end of the rod 31 may be guided further by means of a spring 39 attached to the upper end of the rod and also attached to a screw 40 adjustable up-and-down by means of a nut 41 in a bracket 42 so as to increase or decrease the tension or biasing effect of the spring 39, as desired under particular conditions.

When no. current is being supplied to the vcoil 23, the spring 39 by its biasing action,

maintains the rod 31 and stylus holder 27 in inoperative positions, those shown in Fig. 1, where the recording stylus 26 is out of engagement with the record. However, as soon as the supply current or carrying current of a circuit containing the coil 23 is allowed to become effective, it tends, by the well known principle of the solenoid, to centralize the rod 31' with respect of the coil 23. Since the part of the rod 31 protruding beyond the upper end of the coil 23 exceeds 1n length that part of the rod which protrudes below the lower end of the coil 23, the tendency of the carrier orsupply current is to draw the rod 31 downwardly. In this position, the stylus 26 is pressed against the record with a force which is substantially the same whether a thick or thin record is used. When the carrier current is varied in accordance with sound vibrations, or when it has superposed upon it a modulating current, the recording stylus 26 is vibrated in accordance with the sound vibrations changing or modulating the carrier current. Hence, the rod 31 and stylus 26 are vibrated by the solenoid coil 23 to cause a groove, Varying in depth with the characteristics of sound, to be engraved upon the waxy record surface. 7

tremely light so as to have very little, if any, appreciable inertia. Hence, the vibrating movements of the stylus holder will be substantially in accordance with the sound to be recorded, and by this means, the sound'record.

will be faithful and clear, and will have snflicient amplitude to reproduce with the desiredvolume. \V

In order that the device may operate with greater certainty and so that thesound re-,

corded will have sufiicientvolume under all conditions, the present invention proposes making therod 31 a part of amagnetic circuit. This magnetic circuit is preferably excited by a coil 42 placed around a permanent magnet 43 whose one arm 44 comprises the lug which supports the stylus holder and whose other arm 45 is engaged by the knife-bar 36 for the upper end o'ftherod 31.

Preferably, the current passing throughmagnetic material so as to constitute a free ,i

path for the magnetism.

In Fig.- 4, here is shown improved electrical means for operating the recording apparatus shown in Figs. 1 to 3. In this circuit a telephone-transmitter is connected by a wire 51 through the primary 52 of an induction coil 53 and a wire '54 to one side of a battery 55, while a wire 56 from the transmitter 50 is connected to the other side of the engagement with the record surface in the manner above explained; This is accomplished by connecting a wire 58 leadmg from the coil 23 to the induction coil secondary 57 by connections between the secondary 59 of the induction coil 53 and the solenoid coil 23 which consists of the wire 58 leading from the coil 23 to one side of the secondary 59 and a wire 63 leading to a condenser 64 whose other side is connected to the wire 62 leading. to the coil23..

It will therefore be seen that the present invention comprisesymeans-for increasing the strength of the electromotiveforce of the voice'current through the operation of an induction coil and yet permits or causes the solenoid coil 23 to be normally energized by the battery current so as to cause the stylus to be moved to and held in operative position by the operation of the switch 57.

In cases where the rod 31 is made to form parts of a closed magnetic circuit, as by the provision of the coil 42 and magnet 44, the system also includes a wire 65 connecting one side of the coil 42 with one side of the battery and a wire 66 connecting the other side of the coil 52 with the wire 61 which leads to the switch 57 connected to the other side of the battery 55; Hence, when the switch 57 is 0 en, both the coil 23 and the coil 42 are ren cred inoperative.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others. 7

Having described the invention, what is claimed as new and for which it is desired to obtain Letters Patent, is: 2 1. A phonographic recording device comprising recording means for engaging a record, and a solenoid connected to said recording means for bringing the recording means to recording position, and to actuate the recording means in its recording position, said \105 solenoid being in circuit with a telephone transmitter and vibrating said recording which is connected by wires and 61 to the switch '59 leading to the battery 55. The other wire 62 of the coil 23 is connected to the wire 51 which leads to the other side of the battery 55 through the primary 52 of the induction coil.

When the switch 57 is closed and sound waves are impressed upon the transmitter 50, the current flowing through the primary 52 of the induction coil is caused to alternate or fluctuate by the operation of the transmitter,

and this alternating current causes an alternatmg or voice current which 15 increased in strength or the electromotive force is in-' means in accordance with variations in said circuit caused by said telephone transmitter.

2. 'A- phonographic recording device com prising a carriage, recording means on the carriage to engage a record, means on thecarriage tendmg to normally keep said re-.

cording means inoperative, and electrically operated means for moving said recording means independently of the carriage into operative position.

3. A phonographic recording device comprising a stylus; electrical meansactuated;

by telephonic carrier current for maintaining the stylus in recording position; and

means for impressing upon said electrical means ,yoice or signal currents which operate said electrical means to vibrate said stylus for recording;'

4. A'phonographic recording device comprising a stylus; a solenoid actuated by tele phonlc carrier current for maintaining the stylus in' recording position; and means for impressing on said solenoid voice or signal currents which operate said solenoid to vibrate said stylus forrecording.

5. A phonographic recording device comprising a stylus; electrical means actuated by telephonic carrier current for maintaining the stylus in recording position; means for producing voice or signal currents; means for transforming said voice or signal currents; and means for impressing on the said electrical means the transformed voice or signal currents which operate said electrical means to vibrate said stylus for recording.

6. A phonographic recording device comprising a stylus; a solenoid actuated bytelephonic carrier current for maintaining the stylus in recording position; means for protion, said solenoid being in circuit with a telephone transmitter and vibrating said recording means in accordance wlth variations in said circuit caused by said transmitter, a

separate source of magnetic flux, and means to connect said source to said movable member to maintain'magnetism in said movable member.

8. A phonographic recording device comprising in combination, recording means for engaging a record, a solenoid for holding said recordingmeans in contact with said record and for vibrating said recording means in accordance with the sound vibrations to be recorded, said solenoid comprising a movable magnetic core responsive to magnetic vibra tions caused by voice currents impressed upon said solenoid, and an electroma net including said movable core as a part 0 its magnetic structure.

9. The herein described method of electrically recording sound which consists in causing carrier current tomaintain in record ena gaging position a normally inoperative stylus of an electrically responsive device, and causing said stylus to-be vibrated'as the result of voice or signal currents superimposed upon said electrically responsive device.-

10. A phonographic recording system comprising a transmitter; an inductive coupler; a battery; an electrically operated recorder comprising a stylus; means for feeding direct current from said battery to said recorder to maintain said recorder energized and the stylus thereof in recording positlon; means for feeding direct current to said transmitter; means for feeding voice or signal current produced b the transmitter to the primary of the in uctive' coupler; and means for feeding voice or signal current induced in the secondary of said inductance coupler to the recorder to vibrate the stylus of the recorder.

Signed at Bridgeport, in the county of Fairfield and State of Connecticut, this 2nd day of December, 1925.

HOWARD SELLERS WORRELL. 

